1. Field of the Invention
The present invention related to a magnetic tape cartridge. More particularly, it relates to an improvement in a spring for pushing the top end of a reel shaft of a magnetic tape cartridge.
2. Related Art
A video tape cartridge is generally constructed in such a manner that a pair of circular openings are formed in a bottom plate of a lower half casing which is to be coupled to an upper half casing; a pair of reels around of which video tapes are wound are loosely fitted to the openings and a pressing spring is secured to the inner surface of a top plate in the upper casing so as to press the top end of a projection at the center of the reel by the extreme end of the spring. When the upper and lower casings are coupled together, a front cover 3 is attached in the front of the coupled casings so as to be capable of opening and closing; a pair of reels 4, 5 is put inside the casings in a freely rotatable manner and each of projections 6, 7 provided at the center of reels is pressed by each of the extreme end of a leaf spring 8 as shown in FIGS. 1 and 2. Thus, the conventional VHS type video tape cartridge has been assembled. The leaf spring 8 of the conventional video tape cartridge is, however, so fabricated that it is firmly attached to the inner surface of the top plate in the upper half casing by melt-bonding boss 11 at its central portion and the leaf spring end are greatly curved toward their extreme ends so as to have a sufficient flexibility thereby allowing vertical movement of the reels when the cartridge is placed on a video tape recorder. Accordingly, the direction of a force for pressing the projections 6, 7 of the reels 4, 5 assumes the direction as shown by the arrow mark A which is perpendicular to a plane of the extreme end 9, or 10.
There is a fairly large amount of clearance between each of the inner walls 13 of the winding cores and each of shafts 12 of the video tape recorder inserted into the winding core when a video tape cartridge is mounted on the video tape recorder, on account of which the axial line of each of the tape recorder shafts 12 is not in coincidence with that of each of the reels under condition that the projection 7 of the reel is always pushed inwardly whereby both the axial lines are always deflected toward each other during operations of the video tape recorder. If a magnetic tape wound on the winding core 13 of the reel is drawn out under the condition as described above, a irregular movement of the reel takes place around the shaft of the video tape recorder whereby there occurs a jittering phenomenon due to variations in tensile force in the magnetic tape.